This invention relates to devices for collating and feeding screws, nails and other work articles of the same or similar configuration. Such feeders are utilized for supplying such articles to work stations where the articles may be further collated, transported or packaged or they may be used to carry out various operations such as fastening workpieces together, e.g. fastening hinges to door jambs.
Conventional feeders of screws, nails and other uniform articles include devices such as those described in U.S. Pat. Nos. 2,943,764, 3,071,291 and 4,222,495 which collate articles lying randomly in a receptacle by intercepting the articles with a collating device having one or more channels or slots into which the articles drop and which thus capture the articles in queued fashion. The articles are slidable within the slots so that when the slots are tilted above the horizontal about a pivot point at one end thereof, the queued articles will slide in the downhill direction. In his manner the articles are carried in each slot to the end of the slot at the pivot point. At the pivot point are entrances to a second set of slots which communicate with the respective first slots. The articles moving downward along the first slots will thus be transferred one-by-one in a queue, into the second slots. The second slots are fixed and extend downwardly from their entrances so that the queue of articles will slide down the second slots to an escapement mechanism which will stop the queue and then separate each article from the queue, consecutively depositing each article into a receiver which transports each article individually to an appropriate work station.
A problem with foregoing type of feeder is the tendency of the random articles in the receptacle to cause jams that impede the movement of the queued articles in the first set of slots over to the second slots since the random articles sliding in the box reach the entrances to the second set of slots about the same time as those sliding down in a queue in the first set of slots. An attempt to deal with this problem was made in the nail feeder described in U.S. Pat. No. 3,071,291 by employing a gate midway down the length of the oscillating box to meter a smaller number of nails fed into the forward section of the box for collation. However this increases the complexity of the feeder and the random nails in the forward box section still reach the entrances to the second set of slots a about the same time as do the queued nails. Moreover, this approach further complicates removal of articles from the machine for changeover to feeding another style or type of article.
Screw feeders, such as that described in my U.S. Pat. No. 5,425,473, can operate similarly, but instead of having collating slots communicating with separate queuing slots at a pivot point, the queuing slots are simply continuations of the collating slots, without a pivot, to the escapement. In this design the entire receptacle reciprocates about a pivot transverse to the slots, the pivot being located adjacent the escapement and screw receivers to facilitate transfer of the screws from the slots at the escapement to the receivers.
The described feeders may be used to feed a variety of screws, nails, etc. of different configurations, finishes or sizes and it may be necessary to change from one to another frequently. Each substitution requires laborious and time-consuming clearing from these feeders, by hand, of the screws to be replaced, including those captured in the collating slots. In conventional screw feeders it has been necessary to employ a wire to remove by hand each of the screws in the slots.